Balancing heads for dynamic balancing machines

ABSTRACT

Balancing head used for supporting the opposite ends of a rotor being balanced in a dynamic balance machine constructed with a top head unit adapted to have a rectilinear reciprocatory motion relative to a fixed bottom head unit. A pair of hydrostatic bearings are provided between the top and bottom head units to reduce friction therebetween. A pair of magnetic devices are provided between the top and bottom head units to center the top head unit relative to the bottom head unit and to restrain the override horizontal movement of the top head unit.

United States Patent [151 3,677,093 Hutchings, Sr. {451 July 18, 1972s41 BALANCING HEADS FOR DYNAMIC FOREIGN PATENTS OR APPLICATIONSBALANCING MACHINES 3,452,604 7/ l 969 Schaub ..73/475 157,962 4/1922Great Britain ..73/478 Primary Examiner-James J. Gill Attomey-Johnson,Dienner, Emrich, Verbeck & Wagner ABSTRACT Balancing head used forsupporting the opposite ends of a rotor being balanced in a dynamicbalance machine constructed with a top head unit adapted to have arectilinear reciprocatory motion relative to a fixed bottom head unit. Apair of hydrostatic bearings are provided between the top and bottomhead units to reduce friction therebetween. A pair of magnetic devicesare provided between the top and bottom head units to center the tophead unit relative to the bottom head unit and to restrain the overridehorizontal movement of the top head unit.

8 Clairrs, 6 Drawing Figures BALANCING HEADS FOR DYNAMIC BALANCINGMACHINES BACKGROUND OF THE INVENTION This invention relates to a new andimproved balancing head design used to support a rotor while beingbalanced in a dynamic balancing machine having a sling-type arrangement.

In sling-type balancing machines, the rotor, which is free to swing,must be lifted as it moves away from a static condition. Thisrequired-lifting force becomes substantial as the weight of the rotorincreases and necessitates a proportional increase in the powerrequirements of the drive system for the balancing machine.

This invention provides a new and improved balancing head design thatsubstantially reduces the inherent frictional forces introduced by eachbalancing head and thereby increases the lifting capabilities of thebalancing machine.

SUMMARY OF THE INVENTION The balancing heads incorporating the featuresof this invention are designed to be used on balancing machines thatemploy a sling-type arrangement to allow it to swing while beingbalanced. Since in sling-type of balancing the rotor is actually liftedeach time it is moved from a static condition, the required liftingforce for large rotors, such as a paper mill roll, becomes prohibitorylarge.

This invention reduces the lifting force factor of a dynamic balancingmachine by reducing the friction introduced by the two balancing headsand by reducing the mass of the balancing heads that has to be moved. Tothis end, there are provided hydrostatic bearing means between themovable top head unit and the stationary bottom head unit. Also, amagnetic centering device provides a strong magnetic field of attractionbetween the top and bottom unit to center the top head unit relative tothe bottom head unit without any metalto-metal contact.

DESCRIPTION OF DRAWINGS For a better understanding of this invention,reference may be made to the accompanying drawing, in which:

FIG. 1 is a front perspective view of a sling-type dynamic balancingmachine to illustrate the type of machine the invention could be usedwith;

FIG. 2 is an elevational side view of a balancing head incorporating theprinciples of this invention;

FIG. 3 is a sectional view taken along the line 3--3 of FIG.

FIG. 4 is a sectional view taken along the line 44 of FIG. 2;

FIG. 5 is an end view of the balancing head shown in FIG. 2; and

FIG. 6 is a cross sectional view taken along the line 6-6 of FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1, there isdepicted a balancing machine 10 used to balance a rotor 12. Inparticular, the balancing machine 10 uses a sling-type arrangement toallow the rotor to swing while being balanced. The rotor 12 beingbalanced is supported at its opposite ends by a pair of balancing heads14 which are positioned in a spaced apart relation by a pair ofpedestals 16. The pedestals 16 are detachably secured to base 18 and canbe moved toward and away from each other to accommodate various rotorsizes. Balancing machine 10 includes a pair of swivel booms 20 whichcarry all its electrical controls and instruments, and an endless beltdrive assembly 22.

In balancing machines using sling-type arrangements, such as depicted inFIG. 1, the rotor is free to swingduring the balancing operation and therotor is actually lifted each time it is moved from a static condition.This invention provides a new and improved balancing head design whichsubstantially reduces the inherent frictional restraining forcesintroduced by the balancing heads and thereby increases the liftingforce capabilities of a balancing machine.

Referring to FIG. 2, balancing head 14 comprises a top head unit 24 andbottom head unit 26. Bottom head unit 26 is mounted on pedestal 16 by apair of adjustable leg members 28.

The leveling purposes, the leg members 28 are independently adjustableby turning the nut 30, which seats on collar 32, about the screw 34. Thepair of screws 34 extend downwardly from the bottom surface of bottomhead unit 26 and their upper ends are mounted in recesses 36 by means ofcross pins 38.

The bottom head unit 26 is constructed on an elongated block 40 having araised top center portion 42. A pair of hydrostatic bearings 44 aresecured at the opposite ends of the top center portion 42 by two bolts46. Two passageways 48 (FIG. 6) are drilled, tapped and piped to carryoil from a hydraulic oil supply system (not shown) through block 40 tothe pair of hydrostatic bearings 44. Oil seals 50 are provided inannular recesses formed about the upper end of passageways 48 to preventleakage between the bearings 44 and bottom support block 40.

The use of the pair of hydrostatic bearings 44 provides a friction freecushion of hydraulic oil between the top head unit 24 and the bottomhead unit 26. Hydraulic oil is forced between the bottom flat surface ofthe top head unit 24 and the two hydrostatic bearings 44 and creates alifting force of sufficient magnitude to raise the top head unit 24,rotor receptacle unit 60 and rotor enough to permit the oil to flow overthe entire surface with a resulting oil cushion.

To absorb end thrust and rotatably guide top head unit 24, a pivotdevice 52 is provided comprising a guide block 54 mounted at the centerof the top center portion 42 of bottom head unit 26 and a thrust bearing12 which extends downwardly from the bottom of the support block 58 fortop head unit 24. Guide block, which is secured in place by a pair ofbolts 60, has a pair of parallel upstanding walls 62 for slidablyreceiving thrust bearing 56 to permit the top head unit 24 toreciprocate. Thus pivot device 52 allows the top head unit 24 to move ina rotatable, reciprocable motion relative to the fixed bottom head unit26.

The top head unit 24 is constructed on elongated top block 58, whoseends extend beyond the ends of bottom block 40. Top block 58 serves asthe base for rotor receptacle unit 60 (FIG. I) which could be any of theknown units used with balancing machines.

End plates 62 (FIGS. 2 and 5) are secured to the opposite ends of topblock 58 by bolts 64 and extend downwardly. A horizontal slot 66 isprovided in each end plate 62 near its lower edge and a pair ofhorizontal rods 68 extend therethrough to limit the pivotal movement oftop head unit 24 in either direction. Each rod 68 is threaded into athreaded bore formed in the ends of bottom block 40 and carry aresilient bumper 70 which serves as a stop for the sliding movement oftop head unit 24 relative to the bottom head unit 26.

One of the important features of this invention is the magneticcentering device 74 for the balancing heads 14 which retains the headsin their proper centered position without the usual metal-to-metalcontact. Centering device 74 comprises a pair of upper magnets 76disposed in close proximity to a pair of lower magnets 78. The upper andlower magnets 76 and 78, respectively, consist of two flat, high power,magnetic blanks 80 and 82 with attracting poles in face-to-face relationfastened, respectively, to upper and lower blocks 58 and 40 by a set ofscrews 84 and 86. The retaining force between the opposing pair ofmagnets 76 and 78 is adjustable by placing spacers of variousthicknesses between magnetic blanks 82.

and bottom block 40.

From the foregoing description, it will be appreciated that the use ofhydrostatic bearings 44 allows for frictionless horizontal movement oftop head unit 24. The oil film provided between bearings 44 and topblock 58 lift and support top head unit 24 and the associated rotorreceptacle unit 60.

Furthermore, the use of the magnetic centering device 74 retains theheads 14 in a centered relation without any metalto-metal contact andrestrains the override horizontal movement of the top head unit 24.

I claim:

1. A balancing head for use on a dynamic balancing machine comprising: abottom head unit having a bottom block member adaptable to be mounted onthe base of the balancing machine and a top head unit having a top blockmember, means for coupling said top block member at its center to saidbottom block member to guide said top block member in a rotatablereciprocable motion relative to said bottom block member, bearing meansbetween said top and bottom block to support said top unit, and furthercomprising means for providing a magnetic attraction between said topand bottom blocks to center said top head unit relative to said bottomhead unit.

2. A balancing head as defined in claim 1, further comprising means forlimiting the horizontal movement of said top head unit.

3. A balancing head as defined in claim 1, wherein said means forproviding a magnetic attraction comprises a first magnet supported fromthe bottom surface of said top block member and a second magnet mountedon the top surface of said bottom block member, where said first andsecond magnets are disposed in vertical alignment in close proximitywith their poles arranged in opposite and attracting relation wheneversaid top head unit is moved to a centered position relative to saidbottom head unit.

4. A balancing head as defined in claim 3, wherein said means forproviding a magnetic attraction further comprises means for varying thespacing between said first and second magnets.

5. A balancing head as defined in claim 1, wherein said top block memberhas a raised center portion and said coupling means is disposed at thecenter of said center portion and wherein said hydrostatic bearing meanscomprises a pair of hydrostatic bearings mounted on the top surface ofsaid raised center portion and disposed on opposite sides of saidcoupling means and means for carrying oil to said bearings.

6. A balancing head as defined in claim 5, wherein said means forproviding a magnetic attraction comprises a first pair of magneticblanks mounted to the top surface of said bottom block member onopposite sides of said raised center portion and a second pair ofmagnetic blanks supported from the bottom surface of said top blockmember, where said second pair of magnetic blanks are brought intovertical alignment with and separated a slight distance from said firstpair of magnetic blanks with their poles arranged in opposite andattracting relation whenever said top head unit is moved to a centeredposition relative to said bottom head unit.

7. A balancing head for use on a dynamic balancing machine comprising abottom head unit including a bottom block member adaptable to be mountedon the base of the balancing machine and a top head unit including a topblock member, said bottom block member having a rectangular crosssection and an upper raised center portion, said top block member havinga rectangular cross sectional and having a longitudinal dimensiongreater than the longitudinal dimension of said bottom block member,means for coupling said top block member at its center to the center ofsaid upper raised center portion of said bottom block member to guidesaid top block member in a rotatable reciprocable motion relative tosaid bottom block, a pair of hydrostatic bearings mounted on the topsurface of said raised center portion and disposed on opposite sides ofsaid coupling means, means for carrying oil to said bearings, a firstpair of magnetic blanks mounted to the top surface of said bottom blockmember on opposite sides of said raised center portion and a second pairof magnetic blanks supported from the bottom surface of said top blockmember, where said second pair of magnetic blanks are brought intovertical alignment wit and separated a slight distance from said firstpair of magnetic blanks with their poles arranged in opposite andattracting relation whenever said top head unit is moved to a centeredposition relative to said bottom head unit.

8. A balancing head as defined in claim 7 further comprising a pair ofend plates extending downwardly from the opposite ends along thelongitudinal dimension of said top block member and having a cross slot,and a pair of rods projecting from the opposite ends of said bottomblock in direct alignment with said cross and of sufficient length toride in said cross slots, where the length of said cross slot isselected to limit the horizontal swing of said top head unit.

l l 4 I i

1. A balancing head for use on a dynamic balancing machine comprising: abottom head unit having a bottom block member adaptable to be mounted onthe base of the balancing machine and a top head unit having a top blockmember, means for coupling said top block member at its center to saidbottom block member to guide said top block member in a rotatablereciprocable motion relative to said bottom block member, bearing meansbetween said top and bottom block to support said top unit, and furthercomprising means for providing a magnetic attraction between said topand bottom blocks to center said top head unit relative to said bottomhead unit.
 2. A balancing head as defined in claim 1, further comprisingmeans for limiting the horizontal movement of said top head unit.
 3. Abalancing head as defined in claim 1, wherein said means for providing amagnetic attraction comprises a first magnet supported from the bottomsurface of said top block member and a second magnet mounted on the topsurface of said bottom block member, where said first and second magnetsare disposed in vertical alignment in close proximity with their polesarranged in opposite and attracting relation whenever said top head unitis moved to a centered position relative to said bottom head unit.
 4. Abalancing head as defined in claim 3, wherein said means for providing amagnetic attraction further comprises means for varying the spacingbetween said first and second magnets.
 5. A balancing head as defined inclaim 1, wherein said top block member has a raised center portion andsaid coupling means is disposed at the center of said center portion andwherein said hydrostatic bearing means comprises a pair of hydrostaticbearings mounted on the top surface of said raised center portion anddisposed on opposite sides of said coupling means and means for carryingoil to said bearings.
 6. A balancing head as defined in claim 5, whereinsaid means for providing a magnetic attraction comprises a first pair ofmagnetic blanks mounted to the top surface of said bottom block memberon opposite sides of said raised center portion and a second pair ofmagnetic blanks supported from the bottom surface of said top blockmember, where said second pair of magnetic blanks are brought intovertical alignment with and separated a slight distance from said firstpair of magnetic blanks with their poles arranged in opposite andattracting relation whenever said top head unit is moved to a centeredposition relative to said bottom head unit.
 7. A balancing head for useon a dynamic balancing machine comprising a bottom head unit including abottom block member adaptable to be mounted on the base of the balancingmachine and a top head unit including a top block member, said bottomblock member having a rectangular cross section and an upper raisedcenter portion, said top block member having a rectangular crosssectional and having a longitudinal dimension greater than thelongitudinal dimension of said bottom block member, means for couplingsaid top block member at its center to the center of said upper raisedcenter portiOn of said bottom block member to guide said top blockmember in a rotatable reciprocable motion relative to said bottom block,a pair of hydrostatic bearings mounted on the top surface of said raisedcenter portion and disposed on opposite sides of said coupling means,means for carrying oil to said bearings, a first pair of magnetic blanksmounted to the top surface of said bottom block member on opposite sidesof said raised center portion and a second pair of magnetic blankssupported from the bottom surface of said top block member, where saidsecond pair of magnetic blanks are brought into vertical alignment withand separated a slight distance from said first pair of magnetic blankswith their poles arranged in opposite and attracting relation wheneversaid top head unit is moved to a centered position relative to saidbottom head unit.
 8. A balancing head as defined in claim 7 furthercomprising a pair of end plates extending downwardly from the oppositeends along the longitudinal dimension of said top block member andhaving a cross slot, and a pair of rods projecting from the oppositeends of said bottom block in direct alignment with said cross and ofsufficient length to ride in said cross slots, where the length of saidcross slot is selected to limit the horizontal swing of said top headunit.